Non-invasive investigations of the role of GABAergic inhibitory mechanisms and task induced oscillations in human visual function. (360G-Wellcome-096518_Z_11_Z)

In order to investigate the role of GABAergic inhibition in human vision and attention, we initially plan to conduct at least four experiments studying normal visual function in healthy participants. In the first series of experiments, we aim to relate participants' gamma oscillation frequency, obtained by a MEG recording during exposure to a visual grating, to behavioural performance in visual tasks such as contrast detection, contrast discrimination, orientation discrimination, and large-field motion detection. Because there is evidence that gamma oscillation frequency is controlled by the level of GABA in the cortex, if individual differences in this measure can predict behavioural performance in a visual task it would indicate that an aspect of visual processing relies on GABAergic inhibition. In the second phase of the thesis, we will aim to relate pre-stimulus modulations of alpha oscillatory activity, obtained in top-down attentional tasks, to levels of GABA in the visual cortex, measured using MR Spectroscopy. Because there is evidence that alpha modulation reflects ability to bias perception, if individual differences in GABA levels can predict alpha modulation levels, it would indicate that top-down visual attention relies on GABAerQic inhibition.